Utilization of magnetic particles to improve z-axis strength of 3d printed objects

ABSTRACT

A method for improving z-axis strength of a 3D printed object is disclosed. For example, the method includes printing a three-dimensional (3D) object with a polymer and magnetic particles, heating the 3D object to a temperature at approximately a melting temperature of the polymer, and applying a magnetic field to the 3D object to locally move the magnetic particles in the polymer to generate heat and fuse the polymer around the magnetic particles to improve a z-axis strength of the 3D object.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/818,754, filed on Mar. 13, 2020, which was recently allowed, which ishereby incorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to three-dimensional (3D)printed objects and, more particularly, to using magnetic particles witha 3D print material to improve z-axis strength of 3D printed object.

BACKGROUND

Three-dimensional printers can be used to print 3D objects. The 3Dprinters can be used to print a variety of different types of objectsusing different types of materials. Different types of processes can beused for 3D printing. For example, 3D printing can use subtractiveprocesses (e.g., where a block of material is etched to print the finalobject) or additive processes (e.g., printing a 3D objectlayer-by-layer).

One type of additive 3D printing process may be fused depositionmodeling (FDM). The FDM process may dispense a layer of material onto aplatform. A binder fluid may be printed onto the layer of material.Energy may be applied to the layer and portions of the layer thatreceive the binder fluid may be fused together. The process may berepeated and the non-fused portions of each layer may be removed via ade-caking process. However, current FDM processes may suffer fromrelatively weak z-axis strength (e.g., a cross-sectional direction ofthe layers).

SUMMARY

According to aspects illustrated herein, there is provided a method,non-transitory computer readable medium, and an apparatus for improvingz-axis strength of a 3D printed object. One disclosed feature of theembodiments is a method that prints a three-dimensional (3D) object witha polymer and magnetic particles, heats the 3D object to a temperatureat approximately a melting temperature of the polymer, and applies amagnetic field to the 3D object to locally move the magnetic particlesin the polymer to generate heat and fuse the polymer around the magneticparticles to improve a z-axis strength of the 3D object.

Another disclosed feature of the embodiments is a non-transitorycomputer-readable medium having stored thereon a plurality ofinstructions, the plurality of instructions including instructionswhich, when executed by a processor, cause the processor to performoperations that print a three-dimensional (3D) object with a polymer andmagnetic particles, heat the 3D object to a temperature at approximatelya melting temperature of the polymer, and apply a magnetic field to the3D object to locally move the magnetic particles in the polymer togenerate heat and fuse the polymer around the magnetic particles toimprove a z-axis strength of the 3D object.

Another disclosed feature of the embodiments is an apparatus comprisinga processor and a computer readable medium storing a plurality ofinstructions which, when executed by the processor, cause the processorto perform operations that print a three-dimensional (3D) object with apolymer and magnetic particles, heat the 3D object to a temperature atapproximately a melting temperature of the polymer, and apply a magneticfield to the 3D object to locally move the magnetic particles in thepolymer to generate heat and fuse the polymer around the magneticparticles to improve a z-axis strength of the 3D object.

BRIEF DESCRIPTION OF THE DRAWINGS

The teaching of the present disclosure can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates a block diagram of a system of the presentdisclosure;

FIG. 2 illustrates a schematic diagram of printing a 3D object using apolymer and magnetic particles of the present disclosure;

FIG. 3 illustrates another schematic diagram of printing a 3D objectusing a polymer and magnetic particles of the present disclosure;

FIG. 4 illustrates a flowchart of an example method for improving z-axisstrength of a 3D printed object of the present disclosure;

FIG. 5 illustrates a high-level block diagram of an example computersuitable for use in performing the functions described herein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures.

DETAILED DESCRIPTION

The present disclosure broadly discloses a method and print materialthat includes magnetic particles to improve z-axis strength of 3Dprinted objects. As discussed above, some 3D printing processes may usean FDM process. However, the bond between each layer may be relativelyweak. Thus, the z-axis strength (e.g., an axis that runs verticallythrough each layer of the 3D object) may be relatively weak.

The present disclosure provides a unique print material for 3D printingthat includes magnetic particles. The print material may be in a powderform or a filament form and may be dispensed for FDM 3D printingprocesses. A magnetic field may be applied after each layer is printedto generate a magnetic field, locally move the magnetic particles togenerate heat, and further locally fuse the polymer powder betweenlayers to improve bond strength between layers. In addition, themagnetic field may align the magnetic particles to further improve bondstrength. As a result, the methods and print materials of the presentdisclosure may improve the z-axis strength of the 3D printed object.

FIG. 1 illustrates an example system 100 of the present disclosure. Inone embodiment, the system 100 may include a 3D printer 102, an oven 104and an apparatus 106 to apply a magnetic field 116. Although the oven104 and the apparatus 106 are illustrated as separate devices, it shouldbe noted that the oven 104 and the apparatus 106 can be combined assingle device.

In one embodiment, the 3D printer may include a supply of print material114 to print a 3D object 108. The 3D printer 102 may include a printhead112 to dispense a printing fluid on a layer of the print material 114.The 3D object 108 may be printed layer-by-layer. Although the 3D object108 is shown as a sphere in FIG. 1, it should be noted that any shapedobject may be printed. The 3D object 108 can be printed to differentshapes, sizes, and complexities.

In one embodiment, the print material 114 may use a combination of apolymer and a magnetic particle to improve the strength of a z-axis 110of the 3D object 108. The z-axis 110 may be a direction that runsvertically through each printed layer of the 3D object 108. The magneticparticles may range from 10 nanometers (nm) to 10 microns (μm) and 0.1weight percent (wt %) to 15 wt % depending on whether the print material114 is dispensed as a powder or a filament.

As discussed in further details below, the magnetic field 116 applied tothe 3D object may help to align the magnetic particles in the 3D object108. The alignment of the magnetic particles may improve the z-axisstrength due to the magnetic attraction of the magnetic particles. Inaddition, the magnetic field 116 may create localized heating frommovement of the magnetic particles to create more inter-layer fusing andinter-layer polymer chains for further improved z-axis strength of the3D object 108. For example, the localized movement may create frictionof the magnetic particles to generate heat. In addition, magneticinduction and hysteresis may generate heat.

In one embodiment, the 3D printer 102 may be any type of 3D printer. Forexample, the 3D printer may be a selective laser sintering (SLS)printer, a fused deposition modeling (FDM) printer, and the like. Theprint material 114 may be provided in a powder form for SLS printers orin a continuous filament for FDM printers.

FIG. 2 illustrates a schematic diagram of a 3D printer that uses a printmaterial 114 where polymers 202 and magnetic particles 204 are mixedtogether. The combination of the polymer 202 and the magnetic particles204 can then be dispensed to print each layer of the 3D object 108.

FIG. 2 illustrates an example of a powder based combination of thepolymers 202 and the magnetic particles 204 in a supply/container 214.For example, the powder based combination may be used in an SLS 3Dprinter.

In one embodiment, the polymers 202 may include materials such aspolylactic acid (PLA), nylon (e.g., nylon 6, 10, or 12), polycarbonate,polyethylene terephthalate (PET), high density polyethylene (HDPE),polypropylene, polystyrene, acrylonitrile butadiene styrene (ABS), andthe like. The polymers 202 may be dispensed in a powder form having anyaverage diameter size appropriate for a particular 3D printer 200.

In one embodiment, the magnetic particles 204 may include magneticmetals such as ferrites, iron oxides, ferrite and silicon dioxide (SiO₂)core-shell nanoparticles, magnetic/metallic nanoparticles, iron, cobalt,nickel, metallic alloys thereof, and the like. For a powder based printmaterial 114, the magnetic particles 204 may have an average particlediameter size of 1 nm to 5 μm. In one embodiment, the average particlediameter size may be approximately 50 nm to 3 μm. In one embodiment, theaverage particle diameter size may be approximately 75 nm to 1 μm.

In one embodiment, the magnetic particles 204 may comprise approximately0.1 wt % to 15 wt % of the print material 114 (e.g., the total weight ofthe combination of the polymers 202 and the magnetic particles 204). Inone embodiment, the magnetic particles 204 may comprise approximately 3wt % to 10 wt %. In one embodiment, the magnetic particles 204 maycomprise approximately 4 wt % to 6 wt %.

In one embodiment, the magnetic particles 204 may be blended with thepolymers 202. The magnetic particles 204 and the polymers 202 may beblended in a temperature controlled blender with high blending power sothat the magnetic particles 204 may be partially embedded onto thepolymers 202.

In one embodiment, the combination of the polymers 202 and the magneticparticles 204 may be dispensed onto a platform 210 to form a layer 212₁. Under the control of a processor ora controller, a printhead 206 maydispense a printing fluid onto desired portions of the layer 212 ₁. Theprinthead 206 may be moved along an x-y coordinate plane above the layer212 ₁. The printing fluid may be a binder that helps melt the polymers202 to form portions of the 3D object 108 that is printed when exposedto an energy source 208. The portions that do not receive the printingfluid may not be fused and may be removed during a de-caking processafter all of the layers 212 ₁ to 212 _(n) are printed.

The platform 210 may be moved vertically (as shown by an arrow 218).After the layer 212 ₁ is printed, the platform 210 may be lowered toreceive another layer 212 _(n) of the polymers 202 and the magneticparticles 204. The printing process may be repeated for each layer 212 ₁to 212 _(n).

As noted above, FIG. 2 illustrates an example for an SLS printer.However, the 3D printer 200 may also be a FDM printer that prints with acontinuous filament. As a result, the magnetic particles 204 may becombined with a continuous filament of the polymer 202. The filament canbe formed to include both the polymer 202 and magnetic particles 204.

In one embodiment, the magnetic particles 204 can be absorbed or fusedonto the extruded filament of the polymers 202 during a drawing process(e.g., when the filament of polymers 202 is above a melting temperatureduring extrusion). The magnetic particles 204 can be powder sprayed ontothe extruded filament of polymers 202 to be combined as a layer of thepolymers 202 is deposited.

In one embodiment, when the polymers 202 and the magnetic particles 204are dispensed as a continuous filament, the average particle diameter ofthe magnetic particles 204 may be approximately 10 nm to 10 μm. In oneembodiment, the average particle diameter of the magnetic particles 204may be approximately 90 nm to 8 μm. In one embodiment, the averageparticle diameter of the magnetic particles 204 may be approximately 1μm to 5 μm.

In one embodiment, the magnetic particles 204 may comprise approximately1 wt % to 10 wt % of the filament (e.g., total weight of the polymers202 and the magnetic particles 204 when delivered as a filament for FDMprinters). In one embodiment, the magnetic particles 204 may compriseapproximately 1 wt % to 8 wt %. In one embodiment, the magneticparticles 204 may comprise approximately 2 wt % to 5 wt %. Thus, thesize of the magnetic particles 204 and the approximate weight percentmay be a function of whether the polymers 202 are delivered in a powderfor SLS printers or as a continuous filament for FDM printers.

FIG. 3 illustrates an example of a printer 300 where polymers 302 andmagnetic particles 304 of the print material 114 are deliveredseparately. In one embodiment, the printer 300 may be an SLS 3D printer.The printer 300 may include a supply container 314 of the polymers 302in powder form. The polymers 302 may be dispensed to form a layer 312 ofthe polymers 302 on a movable platform 310. A printhead 306, under thecontrol of a processor or controller, may dispense a printing fluid ontodesired portions of the layer 312. The printing fluid may be a binderfluid that helps to fuse selected portions of the layer 312 when exposedto an energy source 308 (as described above).

After the layer 312 is printed, a layer 316 of the magnetic particles304 may be dispensed onto the layer 312 of the polymers 302. In oneembodiment, the printhead 306 may dispense the printing fluid onto thelayer 316 and expose the layer 316 to the energy source 308.

After the layers 312 and 316 are printed, the platform 310 may belowered or moved vertically (as shown by an arrow 318). The process maythen be repeated until all layers of the 3D object 108 are printed.

In one embodiment, the average particle diameter and weight percent ofthe magnetic particles 304 may be the same as described above for SLS orpowder based printing. For example, the magnetic particles 304 may havean average particle diameter size of 1 nm to 5 μm. In one embodiment,the average particle diameter size may be approximately 50 nm to 3 μm.In one embodiment, the average particle diameter size may beapproximately 75 nm to 1 μm.

In one embodiment, the magnetic particles 304 may comprise approximately0.1 wt % to 15 wt % of the print material 114 (e.g., the total weight ofthe combination of the polymers 202 and the magnetic particles 204). Inone embodiment, the magnetic particles 304 may comprise approximately 3wt % to 10 wt %. In one embodiment, the magnetic particles 304 maycomprise approximately 4 wt % to 6 wt %.

Although an example of a powder based printer is illustrated in FIG. 3,the printer 300 may also be a FDM 3D printer that uses a supply of thepolymer 302 in a filament form. Thus, the layer 312 may be formed bydispensing the polymer 302 from an extruded filament. The layer 312 maybe printed (e.g., with the printing fluid from the printhead 306 andfused by the energy source 308). The layer 316 may then be dispensed todeposit a layer of the magnetic particles 304 separately on top of thelayer 312 of the polymer 302.

In one embodiment, the average particle diameter and weight percent ofthe magnetic particles 304 may be the same as described above for FDM orfilament based printing. For example, the magnetic particles 304 mayhave an average particle diameter size of 10 nm to 10 μm. In oneembodiment, the average particle diameter size may be approximately 90nm to 8 μm. In one embodiment, the average particle diameter size may beapproximately 1 μm to 5 μm.

In one embodiment, the magnetic particles 304 may comprise approximately1 wt % to 10 wt % of the print material 114 (e.g., the total weight ofthe combination of the polymers 202 and the magnetic particles 204). Inone embodiment, the magnetic particles 304 may comprise approximately 1wt % to 8 wt %. In one embodiment, the magnetic particles 304 maycomprise approximately 2 wt % to 5 wt %.

Referring back to FIG. 1, after the 3D object 108 is printed with theprint material 114 that includes both the polymer and the magneticparticles, the 3D object 108 may be placed in the oven 104. The 3Dobject 108 may then be heated to a temperature that is close to themelting temperature of the polymer 202 or 302. In other words, thetemperature maybe a temperature that is near the melting temperature ofthe polymer 202 or 302 without causing the 3D object 108 to lose shapefrom melting. For example, the temperature may be approximately 20degrees Celsius (° C.) below the melting temperature of the polymer 202or 302 to approximately the melting temperature of the polymer 202 or302.

After the 3D object 108 is brought up to the desired temperature, themagnetic field 116 can be applied to the 3D object 108. In oneembodiment, the strength of the magnetic field 116 may be approximately1 oersted (Oe). In one embodiment, the magnetic field 116 may help toalign the pole movement of the magnetic particles 204 or 304 in the 3Dobject 108. The alignment of the magnetic particles 204 or 304 may helpcreate a magnetic attraction between the magnetic particles 204 or 304to help improve inter-layer bond strength. As a result, the overallz-axis strength of the 3D object 108 may be improved.

In one embodiment, the magnetic field 116 may be oscillated or pulsed.The oscillation of the magnetic field 116 may create localized movementof the magnetic particles 204 or 304 in the 3D object. For example,oscillation of the magnetic field 116 may cause the magnetic particles204 or 304 to rotate back and forth in accordance with the oscillationpattern of the magnetic field 116. This movement may cause frictionbetween the magnetic particles 204 or 304 and the polymers 202 or 302 tocreate localized heat in various internal locations of the 3D object108. The movement and friction may help to melt the polymers 202 or 302in regions between the layers (e.g., layers 212) of the 3D object 108and around the magnetic particles 204 or 304. The magnetic field 116 mayalso cause magnetic induction and/or hysteresis to generate heat andmelt the polymers 202 or 302 in regions between the layers (e.g., layers212) of the 3D object 108. The melting of the regions between the layersmay promote further mixing and entanglement of the polymer chains toimprove the z-axis strength of the 3D object 108.

In one embodiment, the magnetic field 116 may be oscillated or pulsedata range of approximately 10 hertz (Hz) to 500 megahertz (MHz). In oneembodiment, the magnetic field 116 may be oscillated or pulsed at arange of approximately 250 Hz to 100 MHz. In one embodiment, themagnetic field 116 may be oscillated or pulsed at a range ofapproximately 500 Hz to 10 MHz.

In one embodiment, a feedback loop may be implemented. For example, thez-axis strength of the 3D object 108 may be tested after the magneticfield 116 is applied. If testing of the z-axis strength fails, the 3Dobject 108 may be placed back into the oven 104 and/or the apparatus 106for further heating and application of the magnetic field 116.

FIG. 4 illustrates a flowchart of an example method 400 for improvingz-axis strength of a 3D printed object of the present disclosure. In oneembodiment, one or more blocks of the method 400 may be performed by thesystem 100, or a computer/processor that controls operation of thesystem 100 as illustrated in FIG. 5 and discussed below.

At block 402, the method 400 begins. At block 404, the method 400 printsa three-dimensional (3D) object with a polymer and magnetic particles.For example, an SLS or FDM based 3D printer may use a print materialthat comprises a mixture of the polymer and the magnetic particles. Inone embodiment, the SLS based 3D printer may use a powder based polymercombined with the magnetic particles. The SLS based 3D printer may printeach layer with a combination of the polymer and the magnetic particlesor may print separate layers of the polymer and the magnetic particles,as described above.

In one embodiment, for the SLS based 3D printer, the magnetic particlesmay have an average particle diameter size of 1 nm to 5 μm. In oneembodiment, the average particle diameter size may be approximately 50nm to 3 μm. In one embodiment, the average particle diameter size may beapproximately 75 nm to 1 μm.

In one embodiment, the magnetic particles may comprise approximately 0.1wt % to 15 wt % of the print material (e.g., the total weight of thecombination of the polymers and the magnetic particles). In oneembodiment, the magnetic particles may comprise approximately 3 wt % to10 wt %. In one embodiment, the magnetic particles may compriseapproximately 4 wt % to 6 wt %.

In one embodiment, the FDM based 3D printer may use a filament basedpolymer combined with the magnetic polymers. The magnetic particles maybe mixed with the polymer to form the filament. In another embodiment,the magnetic particles may be sprayed onto the filament of the polymeras the filament is extruded. The magnetic particles may then fuse withthe melted polymer that is extruded.

In another embodiment, the FDM based 3D printer may print separatelayers of the polymer and the magnetic particles. For example a layer ofthe polymer may be extruded from the filament and a layer of themagnetic particles may be dispensed on top of the polymer layer, asdescribed above.

In one embodiment, for the FDM based 3D printer, the magnetic particlesmay have an average particle diameter size of 75 nm to 10 μm. In oneembodiment, the average particle diameter size may be approximately 90nm to 8 μm. In one embodiment, the average particle diameter size may beapproximately 1 μm to 5 μm.

In one embodiment, the magnetic particles may comprise approximately 1wt % to 10 wt % of the print material (e.g., the total weight of thecombination of the polymers and the magnetic particles). In oneembodiment, the magnetic particles may comprise approximately 1 wt % to8 wt %. In one embodiment, the magnetic particles may compriseapproximately 2 wt % to 5 wt %.

At block 406, the method heats the 3D object to a temperature atapproximately a melting temperature of the polymer. For example, thetemperature may be approximately 20 degrees Celsius (° C.) below themelting temperature of the polymer to approximately the meltingtemperature of the polymer.

At block 408, the method applies a magnetic field to the 3D object tolocally move the magnetic particles in the polymer to generate heat andfuse the polymer around the magnetic particles to improve a z-axisstrength of the 3D object. For example, after the 3D object is broughtup to the desired temperature, the magnetic field may be applied to the3D object. The strength of the magnetic field may be approximately 1 Oe.

In one embodiment, the magnetic field may be oscillated or pulsed. Theoscillation of the magnetic field may create localized movement of themagnetic particles in the 3D object. For example, oscillation of themagnetic field may cause the magnetic particles to rotate back and forthin accordance with the oscillation pattern of the magnetic field. Thismovement may create localized heat in various internal locations of the3D object to melt regions between the layers of the 3D object. Themelting of the regions between the layers may promote further mixing andentanglement of the polymer chains to improve the z-axis strength of the3D object.

In one embodiment, the magnetic field may be oscillated or pulsed at arange of approximately 10 hertz (Hz) to 500 megahertz (MHz). In oneembodiment, the magnetic field may be oscillated or pulsed at a range ofapproximately 250 Hz to 100 MHz. In one embodiment, the magnetic fieldmay be oscillated or pulsed at a range of approximately 500 Hz to 10MHz.

In one embodiment, the magnetic field may help to align the polemovement of the magnetic particles in the 3D object. The alignment ofthe magnetic particles may help create a magnetic attraction between themagnetic particles to help improve inter-layer bond strength. As aresult, the overall z-axis strength of the 3D object may be improved. Atblock 410, the method 400 ends.

FIG. 5 depicts a high-level block diagram of a computer that isdedicated to perform the functions described herein. As depicted in FIG.5, the computer 500 comprises one or more hardware processor elements502 (e.g., a central processing unit (CPU), a microprocessor, or amulti-core processor), a memory 504, e.g., random access memory (RAM)and/or read only memory (ROM), a module 505 for improving z-axisstrength of a 3D printed object, and various input/output devices 506(e.g., storage devices, including but not limited to, a tape drive, afloppy drive, a hard disk drive or a compact disk drive, a receiver, atransmitter, a speaker, a display, a speech synthesizer, an output port,an input port and a user input device (such as a keyboard, a keypad, amouse, a microphone and the like)). Although only one processor elementis shown, it should be noted that the computer may employ a plurality ofprocessor elements.

It should be noted that the present disclosure can be implemented insoftware and/or in a combination of software and hardware, e.g., usingapplication specific integrated circuits (ASIC), a programmable logicarray (PLA), including a field-programmable gate array (FPGA), or astate machine deployed on a hardware device, a computer or any otherhardware equivalents, e.g., computer readable instructions pertaining tothe method(s) discussed above can be used to configure a hardwareprocessor to perform the steps, functions and/or operations of the abovedisclosed methods. In one embodiment, instructions and data for thepresent module or process 505 for improving z-axis strength of a 3Dprinted object (e.g., a software program comprising computer-executableinstructions) can be loaded into memory 504 and executed by hardwareprocessor element 502 to implement the steps, functions or operations asdiscussed above in connection with the example method 400. Furthermore,when a hardware processor executes instructions to perform “operations,”this could include the hardware processor performing the operationsdirectly and/or facilitating, directing, or cooperating with anotherhardware device or component (e.g., a co-processor and the like) toperform the operations.

The processor executing the computer readable or software instructionsrelating to the above described method(s) can be perceived as aprogrammed processor or a specialized processor. As such, the presentmodule 505 for improving z-axis strength of a 3D printed object(including associated data structures) of the present disclosure can bestored on a tangible or physical (broadly non-transitory)computer-readable storage device or medium, e.g., volatile memory,non-volatile memory, ROM memory, RAM memory, magnetic or optical drive,device or diskette and the like. More specifically, thecomputer-readable storage device may comprise any physical devices thatprovide the ability to store information such as data and/orinstructions to be accessed by a processor or a computing device such asa computer or an application server.

It will be appreciated that variants of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be combined intomany other different systems or applications. Various presentlyunforeseen or unanticipated alternatives, modifications, variations, orimprovements therein may be subsequently made by those skilled in theart which are also intended to be encompassed by the following claims.

What is claimed is:
 1. A method, comprising: printing athree-dimensional (3D) object with a print material comprising a polymerand magnetic particles; heating the 3D object to a temperature atapproximately a melting temperature of the polymer; and applying anoscillating magnetic field to the 3D object to rotate the magneticparticles back and forth in accordance with a pattern of oscillation inthe polymer to create localized heat in various internal locations ofthe 3D object to fuse the polymer around the magnetic particles.
 2. Themethod of claim 1, wherein the printing comprises: printing a layer ofthe 3D object with the polymer; dispensing the magnetic particles on topof the layer; and repeating the printing the layer and the dispensinguntil the 3D object is printed.
 3. The method of claim 1, furthercomprising: testing a z-axis strength of the 3D object after theoscillating magnetic field is applied; and repeating the printing, theheating, and the applying when the z-axis strength of the 3D objectfails testing.
 4. The method of claim 1, wherein a strength of theoscillating magnetic field comprises approximately 1 oersted.
 5. Themethod of claim 1, wherein the oscillating magnetic field is oscillatedat a range of approximately 10 hertz (Hz) to 500 megahertz (MHz).
 6. Themethod of claim 5, wherein the oscillating magnetic field is oscillatedat a range of approximately 250 Hz to 100 MHz.
 7. The method of claim 6,wherein the oscillating magnetic field is oscillated at a range ofapproximately 500 Hz to 10 MHz.
 8. The method of claim 1, wherein theprinting is performed by a selective laser sintering (SLS) printer. 9.The method of claim 8, wherein the magnetic particles comprise 0.1-15weight percent of the print material and have an average particlediameter of 1 nanometer to 5 microns.
 10. The method of claim 1, whereinthe printing is performed using a fused deposition modeling (FDM)printer.
 11. The method of claim 10, wherein the magnetic particlescomprise 1-10 weight percent and have an average particle diameter of 10nanometers to 10 microns.
 12. A non-transitory computer-readable mediumstoring a plurality of instructions, which when executed by a processor,cause the processor to perform operations, the operations comprising:printing a three-dimensional (3D) object with a print materialcomprising a polymer and magnetic particles; heating the 3D object to atemperature at approximately a melting temperature of the polymer; andapplying an oscillating magnetic field to the 3D object to rotate themagnetic particles back and forth in accordance with a pattern ofoscillation in the polymer to create localized heat in various internallocations of the 3D object to fuse the polymer around the magneticparticles.
 13. The non-transitory computer-readable medium of claim 12,wherein the printing comprises: printing a layer of the 3D object withthe polymer; dispensing the magnetic particles on top of the layer; andrepeating the printing the layer and the dispensing until the 3D objectis printed.
 14. The non-transitory computer-readable medium of claim 12,further comprising: testing a z-axis strength of the 3D object after theoscillating magnetic field is applied; and repeating the printing, theheating, and the applying when the z-axis strength of the 3D objectfails testing.
 15. The non-transitory computer-readable medium of claim12, wherein a strength of the oscillating magnetic field comprisesapproximately 1 oersted.
 16. The non-transitory computer-readable mediumof claim 12, wherein the oscillating magnetic field is oscillated at arange of approximately 10 hertz (Hz) to 500 megahertz (MHz).
 17. Thenon-transitory computer-readable medium of claim 16, wherein theoscillating magnetic field is oscillated at a range of approximately 250Hz to 100 MHz.
 18. The non-transitory computer-readable medium of claim17, wherein the oscillating magnetic field is oscillated at a range ofapproximately 500 Hz to 10 MHz.
 19. The non-transitory computer-readablemedium of claim 17, wherein the printing is performed by a selectivelaser sintering printer or a fused deposition modeling printer.
 20. Amethod, comprising: printing a three-dimensional (3D) object with aprint material comprising a polymer and magnetic particles, wherein themagnetic particles have an average particle diameter of 50 nanometers to3 microns and comprise 3 to 10 weight percent of the print material;heating the 3D object to a temperature at approximately a meltingtemperature of the polymer; and applying an oscillating magnetic fieldto the 3D object to align the magnetic particles in the polymer and torotate the magnetic particles back and forth in accordance with apattern of oscillation to generate heat that melts regions betweenlayers of the 3D object to fuse the polymer around the magneticparticles and to promote entanglement of polymer chains between thelayers.